Shear relief check valve for flushing passageways of earth penetrating tools



1965 w. A. KISTLER, JR 3,

SHEAR RELIEF CHECK VALVE FOR FLUSHING PASSAGEWAYS 0F EARTH PENETRATING TOOLS Filed Nov. 1, 1962 w MEDOE WILLIAM A. KISTLER,JR.

INVENTOR.

BY Q

2 ATTORNEY United States Patent 3,213,949 SHEAR RELIEF CHECK VALVE FOR FLUSH- ING PASSAGEWAYS 0F EARTH PENETRAT- ING TOOLS William A. Kistler, Jr., Houston, Tex., assignor to Hughes Tool Company, Houston, Tex, a corporation of Delaware Filed Nov. 1, 1962, Ser. No. 234,664 Claims. (Cl. 175232) The present invention lies in the field of auxiliary devices used with earth penetrating tools, in particular devices used to obtain a measure of control over the flow of flushing fluid used in drilling with such tools. Such a tool is typically suspended from the lower end of a long string of hollow drill pipe through which a flushing fluid or mu is circulated down to the bit and jetted therefrom through a number of nozzles or watercourses. This fluid is then circulated upwardly through the annulus between drill pipe and borewall, carrying the rock cuttings to the surface.

In recent years it has become a common practice to use large pressure drops over such tools to obtain high velocity streams of flushing fluid striking the bottom of the borehole. This is done primarily by using replaceable nozzles with quite small orifices therein, e.g., as small as A" or A in a Tricone 3-cone rotary bit of 8% diameter having three flushing fluid passageways, such nozzles being replaced by others with a different orifice diameter under a different set of drilling conditions (type and depth of formation, rotary speed, weight on bit, mud weight, etc.). While such small orifice nozzles have served admirably their intended function of providing high velocity mud streams on bottom, they also create special problems. The small openings are likely to become easily plugged, and they are not well adapted to the circulation of lost circulation materials, i.e., course materials circulated down the drill string and bit to plug a porous zone which threatens to absorb all of the drilling fluid. They also create special problems when the bit is being run into the hole or pulled from the hole, as the mud standing in the string does not flow into or out of the nozzle openings at a high rate of speed. It is usually necessary to lower or raise the drill string and bit rather slowly to avoid pressure surges which may cave in the wall of the formation.

The present invention provides a means for overcoming some of the named disadvantages associated with jet bits, primarily by providing in place of one nozzle (or more) a special member which is both automatically expellable if the nozzles should become plugged and is controllably expellable in other circumstances. Such special member includes a core or nozzle releasably and sealably secured in the lower end of a bit flushing fluid passageway and having a downwardly extending opening therethrough, a movable member such as a ball seating in the entrance end of such opening to prevent the downward flow of flushing fluid, means to restrain the upward movement of such movable member from a position just above its seating position and yet allowing such limited movement under the influence of a reverse circulation of flushing fluid, and one of more shear pins securing the core to the passageway wall or securing parts of a multipiece core together in such manner that at least a portion of the core may be expelled upon a shearing of the pins. With normal, downward circulation the assembly is activated upon an increase in the normal pressure drop over the bit to a critical or design value, under which condition the pin or pins are sheared and the expellable portion of the core is washed out. Such activation occurs automatically upon a plugging of the operating nozzles of "ice the bit, or controllably by speeding up the mud pump which circulates the flushing fluid.

It can thus be seen that the present invention achieves several objects:

(1) Prior to activation, assuming the bit to be at the bottom of the hole, it blocks normal downward flow through the flushing passageway in which it is installed, thus permitting the use of a lesser number of nozzles of greater orifice than would be the case if nozzles were used in all passageways and thereby reducing the likelihood of unplanned plugging, while at the same time permitting reverse, upward flow under a negative gradient. If such negative gradient occurs when the operating nozzles are plugged and the bit is at the bottom of an extremely deep well, there is a hazard of drill stem collapse because of the high pressure of fluids in the annulus around the drill stem. Such hazard is eliminated when the present invention is employed.

(2) When running a bit into a hole, the shear relief check valve of the present invention permits upward flow of the drilling fluid through its own opening. To better accomplish this object, such opening may be of considerably larger section than the nozzle orifices, with the result that the drilling mud Which is standing in the hole flows relatively rapidly into the drill stem, considerably reducing the pressure surges otherwise felt.

(3) When activated by a shearing of the shear pin and expulsion of all or part of the core, the valve operates to relieve plugged nozzles and permit normal circulation of drilling mud, either alone or with lost circulation materials.

(4) In preparing to pull a bit when there has been no prior occasion to activate the valve, it may be activated to reduce the pressure surges otherwise manifested if the bit is pulled too rapidly. The extra opening thus provided permits a more rapid draining of the mud from the drill stern and makes rapid pulling possible.

The present invention may be more readily understood by reference to the accompanying drawing, in which:

FIGURE 1 illustrates in vertical cross section a preferred embodiment of the present invention as installed in a portion of an earth penetrating tool, e.g., a nozzle boss of a rock bit,

FIGURE 2 is a perspective view of the ball retainer of FIGURE 1,

FIGURE 3 is a vertical cross-section of a modification of the embodiment of FIGURE 1, differing therefrom in that the shear pin underlies the entire core of the valve and is supported by the nozzle boss rather than by a sleeve releasably secured between the boss and the core,

FIGURE 4 depicts in vertical section an alternate embodiment in which a different means is used to retain the ball in place, this view showing the ball in the raised position it would occupy during reverse circulation, and

FIGURE 5 is another vertical section of the FIGURE 4 embodiment, on a sectioning plane disposed at right angles to that of FIGURE 4, the only other diiierence being that the ball is shown in seating position, as during normal, downward circulation.

Referring now to FIGURES 1 and 2, the embodiment there shown is disposed in nozzle boss 1 having flushing passageway 2 therethrough, such passageway being counterbored from its lower end 3 to form shoulder 4. Ball retainer or wire cage 5, comprising the two U- shaped inverted wires or rods 6 secured together by welding at their closed ends 7 and with their free ends bent to form outwardly extending hooks 8, is inserted in flushing passageway 2 so that hooks 8 are engaged by shoulder 4. Two U-shaped wires 6 are used to prevent the upward movement of the ball 9 in the spaces therbetween, but more may be used as necessary.

Core assembly 11, having an outside assembly only slightly less than the diameter of the counterbore, is slidably mounted in the lower end of passageway 2 to press hooks 8 of ball retainer against shoulder 4, core assembly 11 being secured against downward movement by a conventional snap ring 12 lying partly in the indicated groove in boss 1 and partly underlying the bottom of core assembly 11. A conventional O-ring 13 is used to prevent leakage between core assemby 11 and the counterbore of boss 1, such O-ring 13 lying either in the indicated groove in the borewell, in a similar groove in the outer periphery of the core assembly, or in registering halfgrooves in both members.

The core assembly 11 of FIGURE 1 consists of an expellable inner member or core 14 and an outer member or shell 15, core 14 being slidable within shell 15 and in sealing fashion by virtue of O-ring 16. Core 14 has an axial opening 17 therethrough, flared at the upper end to provide a seat 18 for ball 9. The two members are secured together by shear pin 19 extending through the indicated registering openings extending transversely through their walls. It should be noted that in the complete assembly snap ring 12 underlies only the shell 15 of core assembly 11.

The modification of FIGURE 3 differs from that of FIGURE 1 in that the shear pin 19' underlies core assembly 11' and extends into holes in the nozzle boss 1'. While this assembly is shown as consisting of the separate core 14 and sleeve or shell 15', it is apparent that these two pieces may be integrated into one and that O-ring 16 may be eliminated. No snap ring is necessary, of course, as shear pin 19 serves the dual function of securing the core assembly in the nozzle boss and acting as the rupturable member.

In the embodiment of FIGURES 4 and 5, the shear pin 19 serves as the rupturable member permitting expulsion of core 14 from sleteve 15 and cooperates with the link or eye screw 21 to restrict the upward movement of ball 9. The shaft or stem 23 of the eye screw is preferably threaded and engages like threads in ball 9' to secure the two members together, but may be extended therethrough and secured by other conventional means, particularly if the ball is composed of such highly resilient material that a threaded engagement is not feasible.

FIGURE 4 shows ball 9' in the extreme upward position it would occupy under the influence of violent reverse circulation and the restraining effect of the contact between eye screw 21 and shear pin 19, while FIGURE 5 shows the ball in its normal seating position in the downwardly converging wall or seat 18 defining the upper end of opening 17. These figures also illustrate an optional structure for retaining core assembly 11" in the flushing fluid passageway, one disclosed by Kistler in U.S. application 702,060, filed December 11, 1957, now abandoned, and in Mandrell, U.S. Patent 3,115,200. Such structure requires the indicated registering grooves in the wall defining passageway 2 and in the outer periphery of core assembly 11" to accommodate snap ring 12. An axial access slot 22 is provided in the outer portion of the core assembly (or in boss 1 or partly in both) for the insertion of a tool to engage the free ends of the ring. When the core assembly is to be inserted or removed from the boss, snap ring 12 is compressed or expanded by such tool so that the snap ring lies wholly within one or the other of the pair of registering grooves. With such retaining structure, passageway 2 may be of uniform bore throughout, eliminating shoulder 4, as the snap ring retains the assembly against both upward and downward movements.

In other respects the FIGURES 45 embodiment is similar to those of FIGURES 1-3, and the many variations described in connection with the latter group may be applied to the former. As one instance, the snap ring shown in FIGURES 45 may be eliminated and replaced with a shear pin underlying the core assembly 11" and extending into nozzle boss 1, as in FIGURE 3 (and obviously the replacement may also be the type snap ring assembly shown in FIGURES 1 and 2. With such double-function underlying shear pin, it is only necessary to extend the loop portion of eye screw 21 so that ball 9' will seat on entrance wall 18 under downward flow and float above it somewhat under reverse flow. With respect to the embodiments shown in both groups of figures, the structure shown in FIGURE 1 and in FIGURES 4-5 are preferred because they are more readily inserted and withdrawn, and because the parts are less likely to become separated than with a separate shear pin which must be inserted through openings in the nozzle boss.

' Balls 9 and 9' may be made of a wide variety of materials, including metals, relatively hard rubber, and the comparatively hard but somewhat resilient plastics such as nylon. The rubber-covered nylon balls sold under the proprietary name Frac balls are eminently suitable because they combine the indicated characteristics with relatively light weight, a quantity of some importance when running a bit into a hole filled with mud.

Although balls 9 and 9' are illustrated only as members having spherical surfaces, it is apparent that such members may also have other outer surfaces, e.g., a downwardly converging conical surface, in which event seat 18 is provided with a similar surface. No problem is presented with respect to a movable sealing member having such shape in the FIGURES 45 embodiment, as the eye screw and shear pin interfit prevent the movable member from assuming a malfunctioning attitude. In the FIGURES 1-3 embodiments it is necessary to shape the movable member and the ball retainer assembly so that the former has no opportunity to become inverted or cocked.

Broadly the present invention is a shear relief check valve for a fluid flushing passageway of an earth penetrating tool which blocks the flow of flushing fluid downwardly through such passageway under pressure gradients below a design or critical value, permits the flow of flushing fluid upwardly under a negative pressure gradient, and is actuable under pressure drops exceeding such design value to permit the downward flow of flushing fluid.

What is claimed is:

1. A shear relief check valve subassembly adapted to be axially inserted in and sealingly secured to the wall of a flushing fluid passageway of an earth penetrating tool containing a multiplicity of such passages to permit reverse flow through such passage, to prevent forward flow therethrough and therefrom under normal positive pressure gradients, and to allow such forward flow at-higher positive pressure gradients, comprising in combination:

a core nozzle assembly consisting essentially of an outer shell and an inner core, the outer periphery of said shell being adapted to sealingly engage said passage wall and said shell being adapted to be releasably secured with respect thereto, said core being slidably inserted within said shell and sealingly disposed therein, said core having an opening extending axially therethrough with a seat at the upper end,

a shear pin extending transversely of and through registering holes in said shell and said core,

a movable member disposed above said seat and adapted to be received therein and to seal said opening, and a wire cage retainer defined by a number of U-shaped wires spaced with respect to each other and with respect to a passage in which said retainer is to be inserted in inverted fashion as to receive said movable member and prevent it from passing between any of the spaces between said wires and said passage, each said wire having its free ends bent outwardly and transversely to form supporting legs, said retainer being supported on the top of said assembly above said core opening and movable member with its loop end facing such opening and its supporting legs surrounding said seat.

2. The shear relief check valve subassernbly of claim 1 adapted to be mounted in one of said tool passageways which is counterbored from its exit end to form a downwardly facing shoulder, said sleeve is adapted to fit into said counterbored portion, and said legs of the wire cage retainer are adapted to be secured between said shoulder and the top of said assembly.

3. In an earth penetrating tool having a fluid flow passageway therethrough terminating in an exit end, a shear relief check valve comprising a sleeve disposed in said passageway adjacent its exit end, means for releasably securing the sleeve to said tool in sealing relationship with the wall of said passageway, a nozzle member disposed within said sleeve in sealing relationship therewith, and slidable from said sleeve at the exit end of the passageway, said nozzle having an axial opening therethrough with an exit end disposed adjacent the exit end of the passageway and an entry end within the passageway flared to define a seat for a movable obturating member disposed thereabove, a movable obturating member of lesser cross section than said passageway and greater than said nozzle opening disposed above and adjacent said entry end of the nozzle Opening and adapted to seat therein to block the flow of fluid from said passageway into the entry end of said opening, a shear pin extending at least partially across said passageway and into registering openings in said nozzle and sleeve, said shear pin thus securing the nozzle to the sleeve at fluid pressures below a predetermined critical value and being shearable at higher values to permit the expulsion of said nozzle from the exit end of the passageway, and an obturating member retainer disposed in said passageway and secured above said nozzle and obturating member, said retainer comprising a number of wires extending across the passageway to define a non-blocking position of said obturating member wherein it lies above the entry end of the nozzle opening to permit fluid flow from said opening into said passageway.

4. A shear relief check valve adapted for slidable insertion in the portion of a fluid passageway of an earth penetrating tool adjacent the exit end thereof, where fluid is normally delivered by said tool, so that the outer periphery of said valve is disposed in sealing relationship with the passageway-defining wall of said tool, said valve comprising an outer sleeve member and an inner core member, the sleeve member having said outer periphery of the valve and being adapted to be releasably secured to said tool, the core member being sealingly disposed within said sleeve and slidable from said sleeve toward said exit end of the passageway, said core having a central opening therethrough adapted to be disposed with its exit end adjacent the exit end of the passageway and its entry end within the passageway, said entry end diverging outwardly from the center of the opening to define a seat for a movable obturating member, a movable obturating member disposed above said seat of lesser cross section than said passageway and larger than said opening and adapted to seat in said entry end to prevent fluid flow from said passageway into said opening, a shear pin extending between said sleeve and core through registering openings in each, and an obturating member retainer adapted to be disposed in said passageway and secured above said obturating member to restrict the movement thereof, said retainer comprising a number of wires extending across said passageway and so spaced as to prevent movement of said obturating member through the spaces therebetween when said obturating member is in a position in said passageway spaced from said seat at the entry end of the nozzle opening.

5. A shear relief check valve subassembly adapted to be axially inserted in and sealingly secured to the wall of a flushing fluid passageway of an earth penetrating tool containing a multiplicity of such passages to permit reverse flow through such passage, to prevent forward flow therethrough and therefrom under normal positive pressure gradients, and to allow such forward flow at higher positive pressure gradients, comprising in combination:

a core nozzle assembly consisting essentially of an outer shell and an inner core, the outer periphery of said shell being adapted to sealingly engage said passage wall and said shell being adapted to be releasably secured with respect thereto, said core being slidably inserted Within said shell and sealingly disposed therein, said core having an opening extending axially therethrough with a seat at the upper end, a shear pin extending transversely of and through registering holes in said shell and said core,

a movable member disposed above said seat and adapted to be received therein and to seal said opening, and a movable member retainer adapted to be disposed above said movable member and secured against movement through said passageway, said retainer consisting of a number of small wires or rods so spaced as to define a non-blocking position for said movable member above said seat and to prevent said movable member from moving through the spaces between said Wires or rods.

12/61 Powers 318 4/ 63 Dougherty 175317 X JACOB L. NACKENOFF, Primary Examiner.

BENJAMIN BENDETT, CHARLES E. OCONNELL,

Examiners. 

4. A SHEAR FELIEF CHECK VALVE ADAPTED FOR SLIDABLE INSERTION IN THE PORTION OF A FLUID PASSAGEWAY OF AN EARTH PENETRATING TOOL ADJACENT THE EXIT END THEREOF, WHERE FLUID IS NORMALLY DELIVERED BY SAID TOOL, SO THAT THE OUTER PERIPHERY OF SAID VALVE IS DISPOSED IN SEALING RELATIONSHIP WITH THE PASSAGEWAY-DEFINING WALL OF SAID TOOL, SAID VALVE COMPRISING AN OUTER SLEEVE MEMBER AND AN INNER CORE MEMBER, THE SLEEVE MEMBER HAVING SAID OUTER PERIPHERY OF THE VALVE AND BEING ADAPTED TO BE RELEASABLY SECURED TO SAID TOOL, THE CORE MEMBER BEING SEALINGLY DISPOSED WITHIN SAID SLEEVE AND SLIDABLE FROM SAID SLEEVE TOWARD SAID EXIT END OF THE PASSAGEWAY, SID CORE HAVING A CENTRAL OPENING THERETHROUGH ADAPTED TO BE DISPOSED WITH ITS EXIT END ADJACENT THE EXIT END OF THE PASSAGEWAY AND ITS ENTRY END WITHIN THE PASSAGEWAY, SIAD ENTRY END DIVERGING OUTWARDLY FROM THE CENTER OF THE OPENING TO DEFINE A SEAT FOR A MOVABLE OBTURATING MEMBER, A MOVABLE OBTURATING MEMBER DISPOSED ABOVE SAID SEAT OF LESSER CROSS SECTION THAN SAID PASSAGEWAY AND LARGER THAN SAID OPENING AND ADAPTED TO SEAT IN SAID ENTRY END TO PREVENT FLUID FLOW FROM SAID PASSAGEWAY AND LARGER THAN SAID OPENING AND TENDING BETWEEN SAID SLEEVE AND CORE THROUGH REGISTERING OPENINGS IN EACH, AND AN OBTURATING MEMBER RETAINER ADAPTED TO BE DISPOSED IN SAID PASSAGEWAY AND SECURED ABOVE SAID OBTURATING MEMBER TO RESTRICT THE MOVEMENT THEREOF, SAID RETAINER COMPRISING A NUMBE OF WIRES EXTENDING ACROSS SAID PASSAGEWAY AND SO SPACED AS TO PREVENT MOVEMENT OF SAID OBTURATING MEMBER THROUGH THE SPACES THEREBETWEEN WHEN SAID OBTURATING MEMBER IS IN A POSITION IN SAID PASSAGEWAY SPACED FROM SAID SEAT AT THE ENTRY END OF THE NOZZLE OPENING. 